UNAIDS has announced a goal of Getting to Zero New HIV infections and Secretary Clinton has announced a goal of an AIDS free generation. Completely eliminating new HIV infections may not be possible in any large population of persons at high risk for HIV, but it is possible that we now have the scientific and public health tools to get very close to zero new HIV infections. Getting close to zero (CTZ) new HIV infections may be operationally defined as reaching an endemic situation where: HIV prevalence is very low and stable, the great majority (80+%) of HIV+ persons are receiving ART, R0 (the basic reproductive rate) < 1.0, HIV incidence is stable and < 0.1/100 person-years, and gender and racial/ethnic disparities in HIV have been minimized. Combined HIV prevention for persons who inject drugs (PWID), has been quite successful in many high-income settings, and it may be possible to achieve close to zero new infections among PWID. Getting close to zero new HIV infections for PWID needs to be studied in the context of two related and very substantial public health problems: drug related sexual transmission of HIV among non-injecting drug users (NIDUs) and hepatitis C virus (HCV) transmission among PWID. New York City has experienced the world's largest HIV and HCV epidemics among PWID, probably the world's largest HIV epidemic among NIDUs, and has implemented combined prevention for PWID and NIDUs. There are four Specific Aims for the proposed research: 1. Determine the extent to which combined prevention is getting close to zero injecting related transmission in NYC. Apply measures of community risk behavior/HIV viremia and community risk behavior/co-infection for describing and measuring such a CTZ situation. Assess whether the current gender and racial/ethnic disparities for IDU transmission of HIV persist in a CTZ situation. 2. Determine the extent to which combined prevention is getting close to zero for drug related sexual (DRS) transmission among non-injecting drug users (NIDUs) in NYC. Apply measures of community risk behavior/HIV viremia and community risk behavior/co-infection for describing and measuring a CTZ DRS transmission endemic situation. Assess whether the current gender and racial/ethnic disparities for DRS transmission of HIV persist in a CTZ situation. 3. Monitor trends in HCV prevalence and conduct a cohort study of HCV incidence among methadone patients to assess the potential for a declining epidemic of HCV among PWID in NYC. 4. Utilize geospatial analysis to characterize hotspots for continuing transmission of HIV, HSV-2, and HCV among drug users in NYC. These will be achieved through continuation of our long-standing research on risk behavior, HIV, HCV and HSV-2 among persons entering drug use treatment in New York (600 new subjects per year), use of electronic health records from our drug treatment programs (6000 patient records per year), and an active collaboration with the city Department of Health.